Page 64 - Oceans

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LIFE ON TIDAL SHORES

Water near the shore contains a lot of nutrients and

drifting food, making the shoreline a rich habitat for
Limpets clamp marine animals. But it is also a very dangerous place.
themselves to
rocks, protected
by their thick The breaking waves can crush any animal that is not
conical shells
concealed in crevices or burrows, and on tidal shores the
falling tide exposes a region where attached animals such

as mussels and barnacles risk drying up under the sun.
≤ Danger area The depth of this intertidal region changes every day,
As the waves crash on the shore, they pick up rocks and stones
and toss them around. On rocky shores, animals can avoid the affecting what can live there, and this creates distinct
worst by creeping into crevices, which also prevents them from
drying out as the tide falls. But most shore animals are very shore zones inhabited by different types of marine life.
resilient, with extremely strong shells or tough rubbery skins.

shore zones >
Different animals and seaweeds can survive high spring tiDe
different periods of exposure by the falling tide.
The lowest parts of the shore are underwater high neap tiDe
nearly all the time, and are exposed only miDtiDe level
during low spring tides. The middle
shore is covered and exposed low neap tiDe
every day, but the upper shore low spring tiDe
shoreline life may be flooded for only a few
hours twice a month, during
high spring tides. Sublittoral zone is
Splash zone Upper shore Middle shore Lower shore always under water
is very dry covered and covered and exposed only by
and barren exposed only by exposed every day low spring tides
high spring tides

≤ living with the tiDes
Most tidal shore animals, such as these sea
anemones, feed only when submerged. They survive
low tide by closing up to retain water. Some do this
more efficiently than others, so they can survive for
longer and colonize higher zones of the shore.

< life zones
Only a few types of animals can live above the
lower shore, within tight limits imposed by the
tide. But they multiply into dense colonies that
form visible bands on rocky shores. On the far
shore of this bay, massed mussels form a black
band below zones of pale brown barnacles and
yellow lichen.